Introduction
What is a substitution reaction?
A substitution reaction is a reaction in which an atom (or group of atoms) in a molecule is replaced by atom or group of atoms.
Substitution reactions are among the most versatile and important reactions in all of organic chemistry.
This is a chain reaction and happens when effected by light.
When a substitutional reaction happens it may have more stages (especially when alkane is involved) untill there are no hydrogen is absent.
This type of reactions happen only to alkenes, cikloalkanes and arenes. We are going to take a look at alkane and benzene.
Alkane
When hydrogen is replaced halogen (fluorine, chlorine, bromine or iodine)as a result, then this reaction is called substitution reaction in which a C-H bond is broken and a new C-X bond is formed. The chlorination of methane, shown below, provides a simple example of this reaction.
Benzene
Now let us look at benzene but first lets recap what we know about it.
Benzene is a planar molecule containing a ring of six carbon atoms each with a hydrogen atom attached
Benzene is replaced by this symbol, where the circle represents the delocalized electron, and each corner of the hexagon has a carbon atom with a hydrogen attached.
So, in aromatic substitution usually the second atom of the cycle substituent on the arene ring, usually hydrogen, is replaced by another substituent. Here is an example:
In this benzene reacts with bromine to form bromobenzene. One brom out of two replaced one hydrogen which now is in a different place with the second brom.
Task
1. A substitution reaction is a reaction in which an atom or group of atoms in a molecule is replaced by atom or group of atoms.
2. To which hydrocarbons the substitution reaction happens to?
3. What are you learning about right now inorganic or organic chemistry?
4. What is the symol of benzene?
5. Which atom is ussualy replaced in a benzene with benzene?
6. What is the substitution reaction effected by?
7. Finish these:
Process
1. Read the inroduction.
2. Go to these pages and learn more about substitution reaction of alkane and benzene (just this).
3. Watch this shor vidoe to understand how substitution happens- SUBSTITUTION REACTIONS ANIMATION.
4. Do the given tasks then compare the answers in Evaluation and count the points you got.
Evaluation
1. A substitution reaction is a reaction in which an atom or group of atoms in a molecule is replaced by atom or group of atoms. (2p)
2. Only to alkanes, arenes and cikloalkenes.(1p)
3. Organic chemistry.(1p)
4.(1p)
5. The second atom is ussualy replaced.(1p)
6. The substitution reaction is effected by light.(1p)
7. For each 4p if correct:
Total: 23p
Conclusion
Congratulations! You have completed the Substitution reaction of alkene and benzene. This is a brief introduction into the substitutional reactions. You have learned how to comlete these reactions, which hydrocarbons are effected by it and what effects them.